Re: [OpenOCD-user] tms320vc5502 with xds100v2 support

[Andrey G. <and...@e-...>]

Paul,

2015-04-11 20:55 GMT+02:00, Paul Fertser <fer...@gm...>:
> Hey Andrey,
>
> On Sat, Apr 11, 2015 at 07:08:36PM +0200, Andrey Gursky wrote:
>> 2015-04-06 19:18 GMT+02:00, Paul Fertser <fer...@gm...>:
>> > On Mon, Apr 06, 2015 at 06:04:46PM +0200, Andrey Gursky wrote:
>> >> I'd like to know details about how to add a new target for openocd.
>> >> How difficult is to add some very basic support like run/halt target,
>> >> then read/write embedded RAM memory? Are these jtag commands common or
>> >> proprietary?
>> >
>> > When JTAG is used for debugging, it's just a transport for a bunch of
>> > vendor-specific commands. Some vendors document those, some do not.
>>
>> Do you have some references, how typical commands look like? And why
>> irlen can be in such big range from 6 to 38?
>
> I suggest you search for file named
> IHI0031A_ARM_debug_interface_v5.pdf , it's the official ARM reference
> for their debug interface. Another option is to look for some EJTAG
> (MIPS) documents.
>
>> Thanks. But it sounds like no jtag tools are here? OpenOCD could be
>> programmed without these at all because all has been done only
>> according to available documentation? Maybe you could advice me a
>> better place to ask about jtag related open-source development, if
>> OpenOCD-list is not a such place?
>
> AFAICT, yes, most of the target support in OpenOCD is done by
> following reference documents and not reversing. I'm unaware of any
> other place, unfortunately, probably UrJTAG ML might help. Another
> possible opportunity to investigating the original code is to try to
> find irscan and drscan functions in the vendor binaries (it's somewhat
> likely that they have functions like that), place breakpoints there
> and log all the invocations.

Thanks for references.

I looked for *scan and found:
... --> PTI_IceScanIr() --> ... --> jsc_ScanBoth16() -->
FtdiReadBuffer() / FtdiWriteBuffer() --> ... --> libftdi --> libusb.
I can't see DR-related things.

According to [1], obtaining a TAPID is straightforward thing and
IDCODE instruction can be scaned out either. But why doesn't it work
in my case (see former mail to Andreas)?

[1] http://events.ccc.de/congress/2009/Fahrplan/attachments/1435_JTAG.pdf

Regards,
Andrey